Can't answer a poorly constructed question.
But use the transformer? Absolutely, as a test at minimum.
The shielding function will still be intact just as it is with a standard RCA ground loop isolator. It simply keeps DC (that may be modulated, ie; noise) from passing down the shield from one device to another.

Beside cost, if this is a better way to shield, why don't the manufacturers break the shield and use a small value cap, in series? It would still act as an AC/RF shield, but there would be no DC connection (unless they're using the shield as THE ground).

I don't remember the last time I heard of a shield that was acting to cause this kind of problem when the cabling was routed correctly (away from major noise sources).